Preheat oven to 350 F° and prepare two small (7x4) or one 9x13" loaf pan with parchment paper and non-stick spray.
In a large mixing bowl, mashing the bananas and then whisk in the eggs, coconut sugar and milk until well combined and fluffy. Add in the coconut oil and vanilla extract and whisk until combined.
In another bowl, stir together the oat flour, protein, baking powder, baking soda and salt and then add it to the wet the ingredients. Use a rubber spatula to stir until combined and no dry spots remain.
In another bowl, place all the streusel topping ingredients together and use a pastry cutter or a fork to combined. The texture should be similar to sand. Top the banana bread batter with the streusel and bake for 18-20 minutes if using the small loaf pans and 40-35 minutes if using the large loaf pan or until a toothpick when inserted come out clean.
Let the banana bread cool completely before cutting into slices and serving.
Notes
This bread is best if stored at room temperature and covered in an airtight container for up to 5 days.